diff --git a/library/src/main/java/com/liulishuo/filedownloader/FileDownloadMessageStation.java b/library/src/main/java/com/liulishuo/filedownloader/FileDownloadMessageStation.java
index 09c9f8ca..62016e38 100644
--- a/library/src/main/java/com/liulishuo/filedownloader/FileDownloadMessageStation.java
+++ b/library/src/main/java/com/liulishuo/filedownloader/FileDownloadMessageStation.java
@@ -22,6 +22,7 @@
 
 import com.liulishuo.filedownloader.util.FileDownloadExecutors;
 
+import java.io.File;
 import java.util.ArrayList;
 import java.util.concurrent.Executor;
 import java.util.concurrent.LinkedBlockingQueue;
@@ -63,10 +64,19 @@ void requestEnqueue(final IFileDownloadMessenger messenger,
             return;
         }
 
-        if (interceptBlockCompleteMessage(messenger)) {
+        // check if messenger.mTask is null
+        // if null, return; according to filedownloader/FileDownloadMessenger.java -> process()
+        // line 200 to 210
+        if (messenger instanceof FileDownloadMessenger
+                && ((FileDownloadMessenger) messenger).hasTask()) {
+            if (interceptBlockCompleteMessage(messenger)) {
+                return;
+            }
+        } else {
             return;
         }
 
+
         if (!isIntervalValid()) {
             // invalid
             // clear all waiting queue.
@@ -179,10 +189,13 @@ public boolean handleMessage(Message msg) {
         private void dispose(final ArrayList<IFileDownloadMessenger> disposingList) {
             // dispose Sub-package-size each time.
             for (IFileDownloadMessenger iFileDownloadMessenger : disposingList) {
-                if (interceptBlockCompleteMessage(iFileDownloadMessenger)) {
-                    continue;
+                if (iFileDownloadMessenger instanceof FileDownloadMessenger &&
+                        ((FileDownloadMessenger) iFileDownloadMessenger).hasTask()) {
+                    if (interceptBlockCompleteMessage(iFileDownloadMessenger)) {
+                        continue;
+                    }
+                    iFileDownloadMessenger.handoverMessage();
                 }
-                iFileDownloadMessenger.handoverMessage();
             }
 
             disposingList.clear();
diff --git a/library/src/main/java/com/liulishuo/filedownloader/FileDownloadMessenger.java b/library/src/main/java/com/liulishuo/filedownloader/FileDownloadMessenger.java
index 80fce2f0..2cbf73a4 100644
--- a/library/src/main/java/com/liulishuo/filedownloader/FileDownloadMessenger.java
+++ b/library/src/main/java/com/liulishuo/filedownloader/FileDownloadMessenger.java
@@ -400,4 +400,8 @@ public String toString() {
         return FileDownloadUtils.formatString("%d:%s",
                 mTask == null ? -1 : mTask.getOrigin().getId(), super.toString());
     }
+
+    public boolean hasTask() {
+        return mTask != null;
+    }
 }
diff --git a/library/src/main/java/com/liulishuo/filedownloader/download/ConnectTask.java b/library/src/main/java/com/liulishuo/filedownloader/download/ConnectTask.java
index 4c528bfc..79d926bf 100644
--- a/library/src/main/java/com/liulishuo/filedownloader/download/ConnectTask.java
+++ b/library/src/main/java/com/liulishuo/filedownloader/download/ConnectTask.java
@@ -31,6 +31,7 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
+import java.util.Stack;
 
 /**
  * The connect task which used for connect to the backend.
@@ -116,18 +117,32 @@ private void addUserRequiredHeader(FileDownloadConnection connection) {
                 String name;
                 List<String> list;
 
+                Stack<String> names = new Stack<>();
+                Stack<List<String>> lists = new Stack<>();
+
                 // add addition headers which is provided by the user
                 Set<Map.Entry<String, List<String>>> entries = additionHeaders.entrySet();
                 for (Map.Entry<String, List<String>> e : entries) {
                     name = e.getKey();
                     list = e.getValue();
+                    names.push(name);
+                    lists.push(list);
+                    /*if (list != null) {
+                        for (String value : list) {
+                            connection.addHeader(name, value);
+                        }
+                    }*/
+                }
+
+                while (lists.size() > 0) {
+                    list = lists.pop();
+                    name = names.pop();
                     if (list != null) {
                         for (String value : list) {
                             connection.addHeader(name, value);
                         }
                     }
                 }
-
             }
         }
     }